The present invention relates in general to systems for configuring the operating state of an instrument and in particular to a system permitting an operator to control instrument configuration by making selections from menus displayed on a screen.
In recent years the number of selectable operating modes for instruments such as oscilloscopes, logic analyzers and the like has greatly increased. For example, many oscilloscopes permit the display of selectable numbers of traces, and each trace ay utilize one of many internally or externally generated time base signals for horizontal control and one of two or more vertical input channels for vertical trace control. Each vertical input channel may have selectable probe coupling and termination modes and may also permit selection between input signal inverting and noninverting modes. Sweep delay modes may be selected wherein a sweep signal controlling one trace is delayed by a selectable time following initiation of a sweep signal controlling another trace.
The advent of computer-based oscilloscopes has permitted a rapid growth in the number of functions which an oscilloscope may perform. For example, a computer-based oscilloscope may utilize selected digitized waveform data stored in a memory to control waveform display, may synthesize such waveform data on the basis of user-defined mathematical expressions, may self-calibrate portions of its circuitry, or may perform numerical measurements on digitized wveform data and display the results.
As the number of selectable oscilloscope operating modes has increased, so have the number and complexity of control pushbuttons and knobs on oscilloscope front panels. Eventually, microcomputer-based oscilloscopes were programmed to display menus listing various operating modes and permitting an operator to choose from among listed operating modes utilizing pushbuttons on the oscilloscope front panel to indicate menu selections. Use of such menus permitted a reduction in the number of pushbuttons needed because the same set of pushbuttons could be utilized to make selections from several alternatively displayable menus.
Many different menus are required to configure the operating state of a complex oscilloscope capable of carrying out plural operations, particularly when the oscilloscope may be configured to carry out each operation in several different ways. Since it is normally impractical to display more than a few menus at a time, menus are often arranged into a "menu tree" wherein a "master" menu enables an operator to select a "mode" menu from among a set, each mode menu including selections enabling the operator to configure the operating mode of a particular oscilloscope operation. Once a particular mode menu is selected, it is displayed, and the operator may make selections from the mode menu to configure a particular aspect of oscilloscope operation. In complex oscilloscopes the operator may be required to traverse several levels of master menus in order to locate and make selections from a particular mode menu, and this renders the configuration of the oscilloscopes operating state time consuming and difficult to learn.
In the case of such a menu tree, each mode menu includes a fixed set of selectable menu items, but it may also be that when the oscilloscope is in a particular operating state, some or all of the menu items should not be selected because the menu items may control operations incompatible with the current operating state of the oscilloscope. Thus while an operator may cause a particular mode menu to be displayed, the operator may be unaware that selections from the menu may have no effect, or may have an unanticipated effect, depending on the current operating state of the oscilloscope.